Supporting means for grinding wheels



June 3, 1941.

June 3, 1941. c EKHQLM 2,244,057

SUPPORTING MEANS FOR GRINDIN G WHEELS Filed Aug. 4, 1939 a Sheets-Sheet 2 INVENTOR HI ATTO NEY June 3, 1941. c. e. EKHOLM SUPPORTING MEANS FOR GRINDING WHEELS Filed Aug. 4, 1939 6 Sheets-Sheet 3 VENTOR (48L 6002 [KHOL M 5 AT RNEY June 3 1941. c EKHOLM 2,244,057

SUPPORTING MEANS FOR GRINDING WHEELS June 3, 1941. c. G. EKHOLM SUPPORTING MEANS FOR GRINDING WHEELS Filed Aug. 4, 1939 INVENTOR 6 Sheets-Sheet 5 Cq/eL Gusmy f/(HOL M if ATT N EY June 3, .1941. c. G. EKHOLM SUPPORTING MEANS FOR GRINDING WHEELS 6 Sheets-Sheet 6 INVENTOR C421. Gusmv [KHOLM Filed Aug. 4, 1939 Patented June 3, 1941 SUPPORTING MEANS FOR GRINDING WHEELS Carl Gustav Ekholm, Lidkoping, Sweden, assignor to Lidkopings Mekaniska. Verkstads Aktiebolag, Fabriksgatan, Lidkoping, Sweden, a corporation of Sweden Application August 4, 1939, Serial No. 288,473 In Sweden August 12, 1938 18 Claims.

The present invention relates to grinding machines of the center as well as the centerless type. The primary object of the invention is to improve and facilitate the shaping of grinding Wheels and of regulating wheels for centerless grinders.

For simultaneous grinding of several different surfaces of a workpiece the grinding wheel must at first be shaped by dressing it by means of a diamond or similar dressing tool. In such cases where the workpiece to be ground has projecting distinct edges between different surfaces the grinding wheel must be shaped with corresponding distinct inwardly directed corners between different surfaces. The shaping of the grinding wheel with such distinct transitions often causes difiiculties or is quite impossible on account of that the support for the timing tools comes in contact with the grinding wheel and prevents the advancing of the truing tool to the end of the rotational surface tohe trued.

According to the invention this disadvantage is avoided thereby that the grinding wheel consists of several sections, which are relatively I movable in axial direction. During grinding these sections are set close to each other, but when the grinding wheel is to be shaped the sections are separated in axial direction. When the sections are axially separated the truing tool can be advanced to the ends of the different rotational surfaces, so that said surfaces when brought together will form sharp corners.

The invention also relates to an improved supporting means in which the sections of the grinding wheel can be axially displaced when the grinding wheel is stationary as well as when it is rotating. By axial displacement of the grinding wheel sections during the grinding operation certain advantages will be afforded as will be clear from. the foiiowing specification:

The invention is more particularly set forth with reference to the accompanying drawings Wherein Fig. 1 is a longitudinal section through an improved supporting means and a composite grinding wheel.

Fig. 2 a cross section along line II--I.I in Fig. 1.

Fig. 3 shows partly in section the grinding wheel arrangement with its different parts separated and a truing device. The truing device forms per so no part of the invention and is therefore only schematically shown.

Fig.. 4 shows a longitudinal section through a modified embodiment of the supporting means according to the invention.

Fig.5 shows a cross section along the line V-V in Fig. .4.

Fig. 6 shows a longitudinal section through a third embodiment of the invention.

Fig. 7 shows on a smaller scale than Fig. 6 a centerless grinding machine in which thegrinding wheel is arranged in accordance with Fig. 6. and

Fig. 8 shows on a greater scale than Fig. 6 the working surfaces of the grinding wheel and the regulating wheel and a work piece to be ground. Corresponding parts in the three shown embodiments are designated with the same numerals.

The grinding wheel shown in Figs. 1-5 is intended for the grinding of work pieces of the formshown at l in Figures 1, 2, 4 and 5. The workpiece I has three cylindrical surfaces 2, 3 and 4 with different diameters intersected by plane surfaces 5' and 6 perpendicular to the longitudinal axis of the work piece.

Before the grinding operation the grinding wheel is shaped with three cylindrical working surfaces 1, 8, 9 intersected by plane surfaces Ill and II. With a view of obtaining distinct edges between the surfaces 2 and 5 resp. 3 and 6 on the work piece it is quite necessary that the corresponding grinding surfaces I, IE! resp. 8, ll form distinct lines of intersection.

The truing of the grinding wheel oan for instance be performed by means of a truing device as schematically shown in Fig. 3. The truin tool proper consists of a diamond H, which is fixed in the end of a rod l3. Rod l3 traverses a housing [4 and is supported by a slide l5, which is slidable on a guide IS. A spring (not shown) acts upon the housing M towards the grinding wheel. The housing I4 is on its underside provided with a feeling member ll, which bears against a guiding template, the guiding profile of which is shown by the dot and dash line l8l8. In order to limit the vibrations of the truing tool the rod l3 must be made rather stout. Therefore rod I 3 would prevent the advancing of the diamond l2 into the corners between the surfaces 1 and I0 resp. 8 and H of the grinding wheel if the grinding wheel were made in one piece.

According to the invention the sections of the grinding wheel can be brought to the position shown in Fig. 3. In this position of the grinding wheel the diamond l2 can 'be advanced to the ends of the cylindrical surfaces 1 and 8 without difficulty. Therefore these surfaces can be trued along their whole length and will-form distinct lines of intersection with the plane surfaces 5 and 6 when the sections of the grinding wheel are brought close to each other as shown in Figs. 1 and 4. In Fig. 3 the path of the diamond point is indicated by a dot and dash line Iii-l9 the difierent parts of which are of equal length and parallel with the corresponding parts As shown brought to their position shown in Figures 1 and 4. The grinding wheel is now in order for grinding of work pieces.

The arrangement for axial displacement of the grinding wheel sections can be constructed in different ways and the invention is not limited to any specifrc construction of this arrangement. In the two embodiments shown in Figures 1-5 the grinding wheel consists of three sections, each of which is supported by a hub 2B, 2!, 22. The hubs are supported by a cylinder 23 which is secured to the grinding wheel spindle 24; which is rotatably mounted on the grinding machine and arranged to be driven'in a manner not pertaining to the present invention. The intermediate hub 2! is securedto the cylinder 23 between a flange 25 and a nut 26. The hubs 2i and 22 are slidably mounted on the cylinder 23 and are held against rotation relative to the cylinder 23 by ribs 2! (Figures 2 and 5) arranged internally in the hubs and engaging with slots in the outer surface of the cylinder. All the parts described above are substantially equal in the two embodiments shown in Figures 1-5, but the operating mechanisms for axial displacements of the sections of the grinding wheel are different.

In the embodiment shown in Figures 1-3 a rod 28 extends in a central bore in the spindle 24. The rod 28 is held within the' bore by a cover 3:! and carries outside of the end of the spindle a hand wheel 29. Within the spindle the rod 28 is formed with two threaded portions 31!, 32, which are threaded in opposite directions but have the same pitch. These threaded portions are in engagement with threaded bores in two four-armed crosses-33, 34 the arms of which ex tend through slots 35 cut out in the spindle 25 and the cylinder 25. The ends of the arms are retained in internal slots in the hubs 20, 22 by holding members 36.

When rod 28 is turned in relation to the spindle by means of hand wheel 29 the hubs 2B, 22 are moved axially in opposite directions, so that the three sections of the grinding wheel are brought to the position shown in Figure 3. In this position the truing of the grinding wheel can be performed in the manner described above. By turning the hand wheel 29 in the opposite direction the grinding wheel sections are returned to the closed position shown in Fig. 1.

In the embodiment shown in Figures 4 and 5 F a tube 3'? is inserted in a longitudinal bore in the spindle 2 3. The solid end portion of the tube 3'1 is traversed in its transverse direction by an arm 39, which extends through slots 35 in the spindle 24 and the cylinder 23 and is out of contact with the walls of said slots. The ends of the arms are inserted into openings in the hubs and fixed to said hubs. A rod 48 extends along the bore of tube 3? and an arm 4| extends through the end of rod 49 in its transverse direction. The arm fill extends through slots in the spindle 24 and the cylinder 23 and its ends are secured to the hub 22.

On the end of the spindle 24 is mounted an operating sleeve 42, which is held to the spindle by a nut '53 in such a manner that it is freely tui'nable in relation to the spindle. The sleeve 42 has a hand wheel 44 made integral therewith and has two internal threaded portions 45 and it, which are threaded in opposite directions but have the same pitch.- The threaded portion E5 is in engagement with an externally threaded portion of the tube 3?, and the threaded portion 35 is in engagement with an externally threaded portion of the rod 36. By turning the operating sleeve 62 the hubs 26, 22 are moved in opposite directions as in the embodiment shown in Figures 1-3.

The two embodiments described above are constructed in such a manner that the sections of the grinding wheel can only be displaced axially when the grinding wheel spindle is at rest. In some grinding operations, however, certain advantages can be obtained through displacement of the grinding wheel sections during the grinding operation itself. Such an operation is, for instance, the grinding of workpieces having outstanding fianges to be ground on their opposite sides. Figures 6-8 show an embodiment of the invention in which the setting of the grinding wheel spindle is static-nary as well as when it is rotating.

As in the two embodiments already described the grinding wheel consists of three sections. The intermediate section 5!! is cylindrical and the two outermost sections 5!, 52 are disc-shaped. The three sections are mounted on hubs 53, 54, 55 each one of which is mounted on an interior hub 5t, 5?, 53. The intermediate hub 51 is secured to the grinding wheel spindle, and the two end hubs 56, 58 are slidably mounted on the grinding wheel spindle, which is mounted in double-row spherical bearings 59, 6D.

In order to reduce the friction between the hubs and the spindle, axially displaceable ball bearings are arranged between the hubs 56, 58 and the spindle. Each such ball bearing consists of a hardened steel bushing BI, 62 pressed into the hub and a hardened steel bushing 63, 6d pressed on to the spindle 24 and a ball retainer 65 resp. $6 placed between the bushings and containing a number of balls distributed in the longitudinal direction of the spindle as well as in the peripheral direction. In the shown embodiment each retainer consists of a cylindrical tube in which is drilled several holes for the balls. The balls are retained by flaps bent out of the material of the tube.

The operating member for axial displacement of the hubs 56, 58 corresponds in principle with the devices shown in Figures 4-5. Thus a tube 3? extends along a longitudinal bore in the spindie 2 and a rod :35 is placed in the tube. The tube 3? and the rod 40 are connected with the hubs 5E, 58 through arms 39, 4|. Slots 35 are cut in the tube El and the spindle 24 and in the bushings 53, 6 as well as in the ball retainers to allow movement'of the arms 39, 4|. The tube 3'5 is connected with a block 68 by means of a double-acting antifriction thrust bearing 61 situated outside of the end of the spindle 24. The rod 40 is connected to another block 10 by means of a double acting antifriction thrust bearing 89, situated outside of the end of the tube 31. The block 68 is slidably but not rotatably mounted on guides H in a housing l2 which is fixedly mounted on the machine. The block 18 is slidably but not rotatably mounted on guides 13 in the block 88. Thus the two blocks are slidable but not rotatable relative to each other and relative to the housing 12. An operating member 14 is rotatably mounted on the end of the housing 12 and is held by a ring 15. The operating member 74 has two internal threaded portions which are in engagement with external threaded portions 16, 11 on extensions of the blocks 98 resp. Iii. The threaded portions in the shown embodiment have equal pitch but are differently directed, i. e. one is right-threaded and the other one leftthreaded.

Owing to the thread-engagement between the member 14 and the blocks 68, 18 turning of the member M results in sliding movements of the blocks in one direction or the other. These movements are transmitted to the tube 31' and E 61, 69, however, the displacements of the tube and the rod from the non-rotatin blocks 68, 18.

is also possible when the grinding wheel spindle is rotating.

A worm-wheel i8 is firmly mounted on the member M between a shoulder i9 and a nut 88.

The worm-wheel 18 is enclosed in a casing 8| in which a worm 82 is rotatably mounted. The worm 82- is in driving engagement with the wormwheel. The casing 8| is loosely mounted on the worm-wheel and is connected with the same in the peripheral direction only through the worm 82. Therefore the member 74 can be turned in two diiferent ways, viz.

I. By turning the whole casing 8!, whereby the worm 82 connects the worm-wheel.

II. By turning the'worm 82 about its own axis by means of a hand wheel 83 (Fig. '7), whereby the worm-wheel is rotated relatively the casing 8 I.

When the grinding wheel sections are automatically displaced during a grinding operation the displacement takes place as stated in section I and the movements of the section are very small. When the grinding wheel sections are to be separated axially for truing, .the displacement is performed as stated in section II, this also being the case whenever the sections are to be manually adjusted relative to each other.

Figure '7 shows a centerless grinding machine with a divided grinding wheel as shown in Figure 6 and having an automatical driving mechanism for displacement of the end sections of the grinding wheel. The grinding machine consists of a bed 84 and three heads 85, 86, 8'! mounted'on the bed. The head 85 supports a regulating wheel 88 and the head 86 supports a work rest 89 and the head 81 supports the grinding wheel which in this figure is designated 90. The regucasing with the l lating wheel head and the grinding Wheel head are slidably mounted on guides in the bed, while -head 81 is firmly mounted on the bed. The

grinding wheel head supports an electric motor 9| from which the grinding wheel is driven through a belt transmission. The regulating wheel 88 is driven from a separate motor not shown in the drawings.

In order to give the machine a great capacity in mass-production of similar work pieces an operating device is arranged for automatically moving the grinding wheel head towards the regulating wheel head and vice versa. The power for the displacement of the grinding wheel slide is delivered by an auxiliary motor 92 mounted on the side of the bed. The motor 92 is connected with the input shaft of a gear box 94, the output shaft 95 of which extends horizontally along the side of the machine bed 84. Shaft 95 carries a worm (not shown) in engagement with a wormwheel (not shown) firmly connected with a curve disc 96 having a closed guiding groove therein. A roller 91 rotatably mounted on the end of a crank arm 98 is situated in the guiding groove and is governed by the Walls of the groove. The crank arm 98 is firmly mounted on a shaft 99 extendin in the transversal direction of the bed 84 below the grinding wheel slide. The shaft 99 carries on its end below the grinding wheel slide a gear wheel, (not shown) in driving connection with a rack secured to the underside of the grinding wheel slide.

When the auxiliary motor 92 is working the curve disc 96 is turned relatively slowly in the direction indicated by an arrow and hereby causes a turning of the arm 98 and a sliding movement of the grinding wheel slide in first one and then the other direction.

When the auxiliary motor 92 is stationary, point I98 on the curve disc 95 is in contact with the roller 97. At this moment the grinding wheel slide is in its position most remote from the regulating wheel slide. During the first part of the rotation of the curve disc 95 the profile portion llll guides the roller 9? and causes a relatively rapid advancing of the grinding wheel slide 8'! towards the regulating wheel slide. The following profile portion i532 causes a continued advancing of the grinding wheel slide with a reduced speed. The following profile portion I03 is shaped as a circular are having its centre situated on the axis of rotation. When this portion comes in contact with the roller 91, the sliding movement of the grinding wheel slide ceases. The following profile portion i84 causes a relatively rapid returning of the grinding wheel slide to its initial position.

In the embodiment of the invention shown in Fig. '7 the described operating device is also utilised for automatical displacement of the grinding wheel sections. For this purpose the shaft i extended and provided with a second worm (not shown) in engagement with a worm wheel (not shown) arranged below the worm, said worm Wheel being firmly connected with a curve disc 585 having a closed guiding groove. The guiding profile of this groove consists of a portion 5&8 in the shape of a circular are having its centre situated on the axis of rotation of the curve disc, and a portion i i? extending helically towards the axis of rotation in the direction opposite to the arrow shown in the drawing, and finally a portion i953 extending helically out from the axis of rotation. A pivotalile double-armed g lever I559 carries in one end a roller iii], which is situated in the guiding groove of the curvedisc Hi5 and is guided by the walls of said groove. The opposite end of the lever is connected with a projecting lug on the casing 8| by means of a link III.

When the auxiliary motor 92 is started the curve disc I05 is thus rotated with the same angular velocity as the curve disc 96. The rotation of the curve-disc I85 results in a turning of the lever I939 in first one and then the other direction. The turning movement of the lever I09 is through the link III transferred to the casing BI (Fig. 6), said casing being connected with the member I4 through worm 82 and wormwheel I8. The turning of the member I4 as stated earlier in this specification results in displacement of the grinding wheel sections 5%, 52 towards each other and from each other.

Figure 8 illustrates the grinding of a rock drill hammer on the centerless grinding machine shown in Figure '7. The hammer consists of a tapering part H2 and two cylindrical parts H3, H4 and a projecting flange situated between said cylindrical part-s and a square end portion I I5. The cylindrical parts I I 3, I M are connected with the flange through fillets I It, II'I.

Before the grinding operation the grinding wheel sections are separated axially by turning the hand wheel I6 and the grinding wheel sections are then trued 'by means of a truing device of the same construction in principle as the truing device shown in Fig. 3. Each of the end sections 50, 52 is trued with a cylindrical working surface I22 and a working surface I23 in the shape of a rotational surface having a generatrice in the shape of a circular arc and a plane annular working surface I24. The intermediate grinding wheel section BI is trued with a cylindrical working surface I25 having a smaller radius than the interior radius of the plane working surfaces I253. The regulating wheel 88 is trued with two cylindrical supporting surfaces intended to bear against the cylindrical surfaces H3, H t of the work piece.

When the truing of the grinding and regulating wheels is completed the regulating wheel slide is set in such a position in relation to the work blade that the regulating wheel will bear against a work piece placed on the work blade and will control the rotation of the Work piece. The grinding wheel slide is set in such a position that the three cylindrical working surfaces of the grinding wheel are situated in a certain distance from the corresponding surfaces of the work piece. Furthermore the grinding wheel sections 50, 52 are set in a somewhat greater mutual distance than the thickness of the flange when not ground. The profile of the divided grinding wheel as ready for the grinding opera tion is indicated in dot and dash lines in Fig. 8. The grinding of a member of work piece can now be started.

The working cycle in grinding a work piece as shown in Fig. 8 consists of the following phases:

I. The point I 80 on the curve disc 96 is in contact with the roller 91, the grinding wheel slide being in its position most remote from the regulating wheel slide. The profile-part I05 of the curve disc IE5 is in contact with the roller 1 II], and thus the grinding wheel sections are axially separated. A work-piece is placed on the work blade 89 either manually or by means of a mechanical infeeding device.

II. The auxiliary motor 92 is started and turns the curve-discs 95, I05 in the directions indicated by arrows. The part IIlI of the curve disc 96 comes in contact with the roller Q1 and causes a relatively rapid advancing of the grinding wheel slide to its working position proper. The circular are shaped part I66 of the curve disc IE5 is still in contact with the roller III], and therefore the grinding wheel sections remain in their separated axial position shown by dot and dash lines in Figure 8.

III. The profile part I82 of the curve-disc 95 comes in contact with the roller 91 and causes a continued feeding movement of the grinding wheel slide but with less speed than during the phase II. The grinding of the three cylindrical surfaces of the workpiece is commenced. The profile part Ifi'I of the curve disc I05 comes in contact with the roller Ill] and slides the grind ing wheel sections together. At the end of this phase the working surfaces 18, I9 come in contact with the work-piece and grind the plane surfaces IIB, H9 and the fillets H5, H6. The profile-part I06 is preferably so shaped that the sliding together of the end sections takes place more slowly during the grinding of these surfaces.

IV. The circular are shaped profile part I03 of the curve-disc 93 comes in con-tact with the roller 9?, whereby the feeding movement of the grinding wheel slide ceases. The profile-part I08 of the curve-disc I05 comes in contact with the roller NB. The direction of movement of the grinding wheel section is now opposed so that they are moved from each other. During this phase the grinding of the cylindrical surfaces of the work-pieces is finished.

V. The profile part I04 of the curve disc 96 comes in contact with the roller 91 and causes a relatively rapid removing of the grinding wheel slide from the work blade. The circular are shaped profile part I06 of the curve-disc I05 comes in contact with the roller I09, whereby the end sections of the grinding wheel remain in their separated position. At the end of this phase the motor 92 is stopped. The ready ground work-piece is taken out of the grinding gap and a new work-piece is inserted, whereafter the working cycle described above will be repeated.

The invention is not restricted to the embodimen-ts described above but includes also other mechanical devices as well as electrical, hydraulical and pneumatical devices for the same purpose. The grinding wheel may be composed of only two but also of more than three sections. In the last mentioned case the operating member preferably consists of an internally threaded sleeve, similar with the member 42 shown in Figure 4 or the member 14 shown in Figure 6. The threaded portions of the sleeve have different thread-pitches and/or different thread-.- directions and the number of threaded portions corresponds with the number of slidable grinding wheel sections. As connecting members between the operating member and the hubs is preferably used a member of tubes telescopically arranged, said tubes being connected with the hubs through arms.

The invention is applicable in connection with grinding wheels of any desired shape, for instance having several cylindrical and conical surfaces and surfaces of rotation having curved generatrices. In such cases where it is important that every grinding wheel section during the truing operation occupies a certain position in relation to the template, the supporting arrangement may suitably be provided with stopping members adapted to stop the grinding wheel sections when they assume their desired positions.

In the embodiment shown in Fig. 6 the sliding bearings may consist of an inner bushing secured. to the spindle and having projecting ribs extending in the axial direction and an outer bushing firmly connected with the grinding wheel hub and having inwardly projecting ribs situated between the first mentioned ribs and a member of balls or rollers inserted between said ribs. Such sliding bearings can also have the function of transmitting the rotation of the spindle to the grinding wheel. As a further alternative the rotation may be transmitted thereby that the spindle and the bore of the hub are polygonal, preferably square in cross section, a member of balls or rollers being inserted between the spindle and the hub in order to reduce the friction in sliding the hubs. When the arms 39, ii are relieved from the function to transmit rotation they need not be in contact with the sleeve 3? and the hub 55 resp. the rod st and the hub so that every sliding friction on account of the movements of the arms is obviated.

The device shown in Fig. 7 may be simplified thereby, that the same curve disc 96 is used for the sliding of the grinding wheel slide and for the sliding of the grinding wheel sections towards and from each other. For this purpose the lever 98 may be made double armed, one arm carrying the roller 96 and the other arm being connected with the casing 8| through a link. In this arrangement the feeding movement of the grinding wheel slide and the sliding together of the grinding wheel sections will take place simultaneously as well as the return movement of the grinding wheel slide and the separating movement of the grinding wheel sections. With regard to the possibility to change the curve disc for various purposes-however, the arrangement shown in Fig. '7 is more advantageous.

in grinding projecting flanges between the movable parts of the grinding wheel there is a tendency of the grinding wheel to give the Workpiece the same peripheral velocity which would result in a reduction or ceasing of the grinding effect. In order to obviate this inconvenience it may be necessary to mount a pressure roller above the work blade to bear against the work piece so that the resistance against the rotation of the work-piece is increased and the workpiece will rotate with the same peripheral velocity as the regulating wheel.

Having thus described my invention, I claim and desire to secure by Letters Patent the following:

'1. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slideable, an operating member being rotatably mounted on the end of the spindle, a number of telescopic shafts arranged in a longitudinal bore in the spindle, a number of threaded portions connected with the shafts and having thread-engagement with the operating members, said threaded portions having different thread directionsl 2. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon, each hub being adapted to carry one grinding wheel element, said hubs being axially slidable on the spindle, an operating member rotatably mounted on the end of the spindle, a number of internally threaded portions in the operating member, a number of shafts slidably but not rotatably mounted in relation to the spindle, each shaft being connected with one hub through arms extending substantially radially in relation to the spindle and each shaft being externally threaded on its end situated outside the end of the spindle, said threaded ends being in engagement with the internally threaded portions of the operating member.

3. A supporting means in accordance with claim 1, characterized therein that the shafts are connected with threaded blocks through the intermediary of thrust bearings, said blocks being slidably but not rotatably mounted and having thread-engagement with the operating member, whereby the hubs may be axially adjusted when the grinding wheel spindle is rotating.

4. In a supporting means for grinding wheels and the like, the combination of a grindingwheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, an operating member being rotatably mounted coaxially with the grinding wheel spindle and being firmly connected with a number of threaded portions, a number of telescopic shafts arranged in a longitudinal bore in the spindle, a number of threaded blocks being slidably but not rotatably mounted, each block having thread-engagement with one 'of said threaded portions and each block being connected with one shaft through the intermedicry of a thrust bearing, preferably an antifriction bearing.

5. Supporting means according to claim 10 characterized therein that the operating member consists of a Worm wheel enclosed in and carrying a casing in which is rotatably mounted a worm in engagement with the worm-wheel, said worm forming the only connection in the direction of rotation between the casing and the worm wheel.

6. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, a number of shafts telescopically arranged in a bore in the spindle, a number of arms connecting each shaft with one hub, a'number of threaded blocks slidably but not rotatably mounted outside the spindle, each block being connected with one of the shafts through the intermediary of thrust bearings, preferably antifriction bearings, a member having a number of threaded portions with different directions and different pitches in thread-engagement with said blocks, a wormwheel firmly connected with the threaded memher, a casing enclosing the worm wheel and supported by the same, a worm rotatably mounted in the casing and being in driving engagement with the worm-wheel, said worm forming the only connection in the direction of rotation between the casing and the worm-Wheel, a hand wheel or the like connected with the worm and situated outside of the casing and means for automatically oscillating the casing, whereby the grinding wheel sections are automatically brought closer to each other and separated from each other.

7. In a supporting means for grinding wheels and the like, the combination of a grinding Wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, a rod being rotatably but not slidably mounted in a bore of the spindle, a hand wheel or the like mounted on the rod outside the end of the spindle, a number of threaded portions formed on the rod and situated inside the spindle, a number of arms connected with the hubs and having internal threads in thread-engagement with the threaded portions of the rod, said threaded portions having different thread-directions.

8. In a supporting means for grinding Wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and each carrying a grinding wheel element, said hubs being axially slidable, an operating member 7 being mounted outside the end of the grinding wheel spindle and connected with the slidable hubs through a number of shafts slidably mounted in a bore of the spindle and arms extending from the shafts to the hubs and being substantially radially disposed relative to the grinding wheel spindle.

9. In a supporting means for grinding Wheels and the like, the combination of a grinding wheel spindle, a cylinder fixedly mounted on the spindle, a number of hubs slidably but not rotatably mounted on the cylinder, an operating member mounted outside one end of the spindle, a number of shafts slidably mounted in a bore in the spindle and operatively connected with the operating member, a number of arms connected with the shafts and extending substantially radially through slots in the spindle and the cylinder and being connected with the slidable hubs.

10. Supporting means according to claim 9 characterized thereby that besides the slidable I hubs there is also a hub fixedly mounted on the cylinder.

11. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle mounted in bearings on both sides of the grinding wheel, a cylinder fixedly mounted on the spindle, a number of hubs slidably but not rotatably mounted on the cylinder, an operating member mounted outside one end of the spindle, a number of shafts slidably mounted in a bore in the spindle and operatively connected with the operating member, a number of arms connected with the shafts and extending substantially radially through slots in the spindle and the cylinder and being connected with the slidable hubs.

12. In combination with a supporting means for grinding wheels having a spindle and a plurality of hubs mounted on the spindle and being axially adjustable relative to the spindle, of a plurality of grinding wheel sections mounted on said hubs axially beside each others, said grinding wheel sections being so shaped, that in one position of the hubs they form sharp edges with each others and in another position of the hubs they are axially separated from each others.

13. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, an operating member being rotatably mounted on the end of the spindle, a number of telescopic shafts arranged in a longitudinal bore in the spindle, a number of threaded portions connected with the shafts and having thread-engagement with the operating members, said threaded portions having different thread-pitches.

14. In a supporting means for grinding Wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, an oper-- ating member being rotatably mounted on the end of the spindle, a number of telescopic shafts arranged in a longitudinal bore in the spindle, a number of threaded portions connected with the shafts and having thread-engagement with the operating members, said threaded portions having different thread directions and threadpitches.

15. A supporting means in accordance with claim 13, characterized therein that the shafts are connected with threaded blocks through the intermediary of thrust bearings, said blocks being slidably but not rotatably mounted and having thread-engagement with the operating member, whereby the hubs may be axially adjusted when the grinding Wheel spindle is rotating.

16. A supporting means in accordance with claim 14, characterized therein that the shafts are connected with threaded blocks through the intermediary of thrust bearings, said blocks being slidably but not rotatably mounted and having thread-engagement with the operating member, whereby the hubs may be axially adjusted when the grinding wheel spindle is rotating. 7

1'7. In a supporting means for grinding Wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, a rod being rotatably but not slidably mounted in a bore of the spindle, a hand wheel or the like mounted on the rod outside the end of the spindle, a number of threaded portions formed on the rod and situated inside the spindle, a number of arms connected with the hubs and having internal threads in thread-engagement with the threaded portions of the rod, said threaded portions having different thread-pitches.

18. In a supporting means for grinding wheels and the like, the combination of a grinding wheel spindle and a plurality of hubs mounted thereon and adapted to carry each one grinding wheel element, said hubs being axially slidable, a rod being rotatably but not slidably mounted in a bore of the spindle, a hand wheel or the like mounted on the rod outside the end of the spindle, a number of threaded portions formed on the rod and situated inside the spindle, a number of arms connected with the hubs and having internal threads in thread-engagement with the threaded portions of the rod, said threaded portions having diiferent thread-directions and thread-pitches.

CARL GUSTAV EKHOLM. 

